Visual inspector for inspecting flat panel display device and visual inspecting method using the same

ABSTRACT

A visual inspector for inspecting a flat panel display device and a visual inspecting method using the same are disclosed. The visual inspector includes an inspection unit including a base frame and a loading stage rotatably coupled to the base frame to load a display panel on a front side thereof and to transmit a light to the flat panel device; a reflective illumination unit installed in the upper space of the inspection unit to illuminate the display panel loaded on the front side of the loading stage; and a transparent illumination unit coupled to the rear side of the loading stage of the inspection unit to illuminate the display panel loaded on the front side of the loading stage.

This application claims the benefit of Korean Patent Application No.10-2005-133992, filed on Dec. 29, 2005, which is hereby incorporated byreference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for inspecting a displaypanel of a flat panel display device, and more particularly, to a visualinspector for inspecting a flat panel display device.

2. Discussion of the Related Art

Flat panel display devices are designed to be smaller in volume andlighter in weight than cathode ray tube display devices. Flat paneldisplay devices include liquid crystal displays (LCDs), field emissiondisplays (FEDs), plasma display panels (PDPs), and light emitting diode(LED) displays.

An apparatus of the related art is used to examine flat panel displaydevices to determine their quality. A light is projected onto thedisplay panel (for example, an LCD panel) using the apparatus and aworker examines light reflected from the display panel to detect andevaluate defects in the display panel that will result in a low qualitydisplay during operation.

A visual inspector is an apparatus for performing a naked eye inspectionof a display panel.

The visual inspector is designed to allow evaluating differences inlight reflection at different illumination angles to determine whetherthe display panel is of inferior quality.

In a visual inspection process according to the related art, reflectiveillumination and transparent illumination are used to perform areflective illumination inspection and a transparent illuminationinspection, respectively.

The visual inspector of the related art includes an illuminationstructure (hereinafter referred to as a “reflective illumination unit”)for providing reflective illumination and another illumination structure(hereinafter referred to a “transparent illumination unit”) forproviding transparent illumination, respectively.

In a visual inspection method of the related art, the transparentillumination unit is positioned at a predetermined distance (inspectiondistance) from a place where the inspection is carried out (hereinafterreferred to as an “inspection unit”) during the transparent illuminationinspection.

During the reflective illumination inspection of the related art, thedisplay panel is inclined at an angle to the vertical direction.Accordingly, the transparent illumination unit may interfere with theinclined display panel if the transparent illumination unit ispositioned near the inspection unit. To prevent this interference, thetransparent illumination unit is moved away form the inspection unit bya predetermined distance when carrying out the reflective illuminationinspection. The time during the movement of the transparent illuminationis “dead time” or time during a visual inspection during whichevaluation of the display panel cannot be performed.

Because of the need to accommodate movement of the transparentillumination unit to perform the reflective illumination inspection, thevisual inspector of the related art has a large overall footprint.Moreover, moving the transparent illumination unit to carry out thereflective illumination inspection increases dead time by the time takento complete the movement of the transparent illumination unit.

When inspecting large sized display panels, the inspection distance mustbe increased in proportion to the size of the display panel, which mayfurther increase the overall footprint of the visual inspector of therelated art.

Limitations in the luminance of the transparent illumination unit of therelated art may limit the precision of the transparent illuminationinspection, particularly when the inspection distance is large.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a visual inspector forinspecting a flat panel display device and a visual inspecting methodusing the same that substantially obviate one or more problems due tolimitations and disadvantages of the related art.

An advantage of the present invention is to provide a visual inspectorfor inspecting a flat panel display device in which a footprint of theoverall apparatus is minimized, the dead time is reduced, and limits onthe luminance of a transparent illumination unit are overcome so thatthe transparent illumination quality inspection can be carried outprecisely, and a visual inspecting method of the flat panel displaydevice using the same.

Additional advantages and features of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription or may be learned from practice of the invention. Theobjectives and other advantages of the invention may be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the invention, as embodied and broadly described herein, a visualinspector for inspecting a flat panel display device includes: aninspection unit including a base frame and a loading stage rotatablycoupled to the base frame to load a display panel on a front sidethereof and to transmit a light therethrough; a reflective illuminationunit installed in the upper space of the inspection unit to illuminatethe display panel loaded on the front side of the loading stage; and atransparent illumination unit coupled to the rear side of the loadingstage of the inspection unit to illuminate the display panel loaded onthe front side of the loading stage.

In another aspect of the present invention, a method for inspecting aflat panel display device using a visual inspector includes: providing adisplay panel to a front side of a loading stage; inclining the loadingstage at a first predetermined angle; illuminating a front side of thedisplay panel to inspect a quality of the display panel; inclining theloading stage at a second predetermined angle; and illuminating a rearside of the display panel to inspect the quality of the display panel.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention.

In the drawings:

FIG. 1 is a side view schematically illustrating an internal structureof a visual inspector for inspecting a flat display device according toan embodiment of the present invention;

FIG. 2 is an exploded perspective view illustrating main parts of aloading frame and a transparent illumination unit of the visualinspector for inspecting a flat panel display device according to anembodiment of the present invention;

FIG. 3 is a side view illustrating a reflective illuminating examinationprocedure using the visual inspector for inspecting a flat panel displaydevice according to an embodiment of the present invention; and

FIG. 4 is a side view illustrating a transparent illuminatingexamination procedure using the visual inspector for inspecting a flatpanel display device according to an embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Reference will now be made in detail to embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

FIG. 1 schematically illustrates a visual inspector for inspecting aflat display device according to an embodiment of the present invention.

As shown in FIG. 1, a visual inspector for inspecting a flat paneldisplay device includes an inspection unit 100, a reflectiveillumination unit 200, and a transparent illumination unit 300.

First, the inspection unit 100 will be described.

The inspection unit 100 is a device with which a worker inspects thequality of a display panel 1. For example, the display panel 1 may be anLCD panel.

The inspection unit 100 includes a base frame 110, a loading stage 120and installation frames 130.

The base frame 110 is a part of a body of the inspection unit 100 and isstructured to stand on a surface such as the ground. The base frame 110can be movable, or can be fixed on a standing stage.

The installation frames 130 are coupled to both upper lateral sides ofthe base frame 110 to support the loading stage 120 and the transparentillumination unit 300. The loading stage 120 is rotatably coupled to theinstallation frames 130 at hinges 131 to rotate the loading stage 120 inthe vertical direction. For example, the loading stage 120 may beindirectly rotatably coupled to the base frame 110 through theinstallation frames 130. In the indirectly coupled arrangement, thehinges 131 are directly coupled to respective sides of the installationframes 130. The hinges 131 are also directly rotatably coupled to theloading stage 120.

The loading stage 120 is structured to support and hold the displaypanel 1 on the front side thereof.

The loading stage 120 may be directly coupled to the respectiveinstallation frames 130 of the base frame 110 to rotate in the verticaldirection at the hinges 131. That is, the hinges 131 may be directlyrotatably coupled with intermediate portions of the respective lateralsides of the loading stage 120. Other arrangements for rotatablycoupling the loading stage 120 to the base frame 110 to allow incliningthe loading stage may be used.

The overall loading stage 120 is made such that light can pass throughthe front surface of the loading stage 120. For example, the loadingstage 120, as shown in FIG. 2, may be made in a lattice shape in whichdistances between the lattices are sufficiently wide to allow effectivetransmission of light to the rear side of the display panel 1.

Alternatively, the loading stage 120 may be formed of a material such astransparent acrylic or other material sufficiently transparent to allowtransmission of light to the rear side of the display panel 1 forconducting an effective visual inspection.

Next, the reflective illumination unit 200 will be described withreference to FIG. 1.

The reflective illumination unit 200 is structured to illuminate thedisplay panel 1 loaded on the front side of the loading stage 120.

The reflective illumination unit 200 is installed in the upper space ofthe inspection unit 100, and includes first illumination unit 210 and areflective plate 220.

The first illumination unit 210 is a light source for providing a lightand one, two, or more first illumination units 210 may be provided.

Moreover, the reflective plate 220 is a device for reflecting the lightprovided from the first illumination units 210 toward the display panel1 loaded on the front side of the loading stage 120. One, two, or morereflective plates may be provided.

Moreover, the reflective illumination unit 200 may further include apolarizing plate 230.

The polarizing plate 230 is a device for polarizing the light reflectedto the display panel 1 by the reflective plate 220 and is installedbetween the reflective plate 220 and the inspection unit 100. One, two,or more polarizing plates may be provided.

In the illustrated embodiment, the first illumination units 210 areinstalled at the rear upper sides of the inspection unit 100, and thereflective plates 220 are installed at the front upper sides of theinspection unit 100. Alternatively, other arrangements of the firstillumination units 210 and the reflective plates 220 that allow lighttransmitted by the first illumination units 200 to be reflected towardsthe display panel 1 may be employed.

Next, the transparent illumination unit 300 will be described withreference to FIGS. 1 and 2.

The transparent illumination unit 300 is structured to illuminate therear side of the display panel 1 loaded on the loading stage 120.

The transparent illumination unit 300 includes a second illuminationunit 310 and a cabinet 320.

The second illumination unit 310 is a light source for illuminating therear side of the display panel 1, and may include any one of afluorescent lamp with internal electrodes such as a cold fluorescentlamp (CFL); a cold cathode fluorescent lamp (CCFL); an externalelectrode fluorescent lamp (EEFL) in which electrodes are providedoutside of a tube; or a light emitting diode (LED).

Moreover, the cabinet 320 provides a space where the second illuminationunit 310 is installed. The cabinet 300 may be made in the form of a boxto be coupled to the rear side of the loading stage 120. In thisconfiguration, the transparent illumination unit 300 can be rotatedtogether with the loading stage 120.

The peripheral and the rear sides of the cabinet 320 may be made of asubstantially opaque material, so that only the light provided from thesecond illumination unit 310 is provided to the display panel 1 throughthe rear side of the loading stage 120. When light is not transmittedthrough the peripheral and the rear sides of the cabinet 320, errors inthe quality determination caused by an external light source (forexample, a sidelight) can be essentially eliminated.

Moreover, the transparent illumination unit 300 further includes acontroller 321 for controlling the second illumination unit 310 and apower supply 322. The controller 321 and the power supply 322 areinstalled in the cabinet 320.

Alternatively, the cabinet 320 of the transparent illumination unit 300may be fixedly coupled to the rear side of the loading stage 120 and thelateral sides of the cabinet 320 may be coupled with the hinges 131 ofthe respective installation frames 130 of the inspection unit 100 torotate thereby. In this case, the loading stage 120 is not coupled withthe respective installation frames 130 but is fixed to the cabinet 320.

Hereinafter, a method of inspecting the display panel 1 with the nakedeye using the visual inspector according to an embodiment of the presentinvention will be described with reference to the accompanying drawings,FIGS. 3 and 4, as follows.

First, the inspection using the reflective illumination (reflectiveillumination inspection) will be described.

For the reflective illumination inspection, the display panel 1 to beinspected is loaded on the front side of the loading stage 120.

During the reflective illumination inspection, the loading stage 120 ispositioned such that the upper side thereof is inclined towards the rearof the inspection unit 100 about the hinges 131 as shown in FIG. 3.

The first illumination unit 210 of the reflective illumination unit 200emits a light, and the second illumination unit 310 of the transparentillumination unit 300 is controlled not to emit light.

The light emitted from the first illumination unit 210 is reflected bythe respective reflective plates 220 to the front side of the displaypanel 1. The reflected light may be polarized by the polarizing plate230 located between the reflective plate 220 and the display panel 1.

A worker standing in front of the inspection unit 100 can view lightreflected from the display panel 1 to visually inspect the display panelfor normal regions, spots, and foreign matter.

An inspection using the transparent illumination (transparentillumination inspection) may be carried out after the reflectiveillumination inspection described above has been completed.

When conducting a transparent illumination inspection, the firstillumination units 210 may be turned off so as not to emit light and theinclination of the loading stage 120 is adjusted to allow light from thesecond illumination unit 310 to be directed towards a worker. In theembodiment illustrated in FIG. 4, the loading stage 120 is inclinedsubstantially vertically so that the front side of the loading stage 120faces the worker. In other words, the loading stage 120 is inclined toan angle of about 90 degrees with respect to the ground.

During the transparent illumination inspection, the second illuminationunit 310 of the transparent illumination unit 300 emits light to providethe illumination.

The emitted light from the second illumination unit 310 is provided tothe rear side of the display panel 1 through the loading stage 120.

A worker standing in front of the inspection unit 100 can view the lighttransmitted through the display panel from the rear to the front sideand can carry out the visual inspection of the display panel 1 fornormal regions, spots, and foreign matter.

The reflective illumination inspection has been described above as beingcarried out before the transparent illumination inspection.Alternatively, the reflective illumination inspection may be carried outafter the transparent illumination inspection or simultaneously with thetransparent illumination inspection.

When the reflective illumination inspection is carried outsimultaneously with the transparent illumination inspection, the firstillumination units 210 may be turned on and the second illuminationunits 310 may be controlled to emit light so that light is provided toboth the rear side and the front side of the display panel 1 loaded onthe front side of the loading stage.

Using the above-described procedures may allow the quality inspection tobe more precisely carried out and more widely applied then can beaccomplished using the visual inspector of the related art.

As described above, integrally forming the inspection unit and thetransparent illumination unit into a single body allows the footprint ofthe overall apparatus to be reduced.

Moreover, the distance between the display panel and the secondillumination unit of the transparent illumination unit may be reduced sothat the luminance limitation associated with the second illuminationunit of the related art can be overcome allowing the quality inspectionto be performed more precisely.

Further, eliminating need to change the position of the transparentillumination unit when carrying out the reflective inspection using thereflective illumination unit allows dead time to be reduced.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1-9. (canceled)
 10. A visual inspecting method using a visual inspectorfor inspecting a flat panel display device comprising: providing adisplay panel to a front side of a loading stage; inclining the loadingstage at a first predetermined angle; illuminating a front side of thedisplay panel to inspect a quality of the display panel; inclining theloading stage at a second predetermined angle; and illuminating a rearside of the display panel to inspect the quality of the display panel.11. The visual inspecting method using a visual inspector for inspectinga flat panel display device according to claim 10, wherein illuminatinga front side of the display panel is carried out prior to illuminating arear side of the display panel.
 12. The visual inspecting method using avisual inspector for inspecting a flat panel display device according toclaim 10, wherein the illuminating a front side of the display panel iscarried out after illuminating a rear side of the display panel.
 13. Thevisual inspecting method using a visual inspector for inspecting a flatpanel display device according to claim 10, wherein illuminating a frontside of the display panel and illuminating a rear side of the displaypanel are carried out simultaneously.
 14. The visual inspecting methodusing a visual inspector for inspecting a flat panel display deviceaccording to claim 10, wherein illuminating a front side of the displaypanel includes reflecting light emitted by a reflective illuminationunit.
 15. The visual inspecting method using a visual inspector forinspecting a flat panel display device according to claim 10, whereinilluminating a front side of the display panel includes polarizingemitted light by a reflective illumination unit.
 16. The visualinspecting method using a visual inspector for inspecting a flat paneldisplay device according to claim 10, wherein illuminating a rear sideof the display panel includes controlling a second illumination unit toemit light.
 17. The visual inspecting method using a visual inspectorfor inspecting a flat panel display device according to claim 10,wherein the second predetermined angle is about 90 degrees.